Variable abrasive belt backup wheel



Jan. 1, 1952 McVEY VARIABLE ABRASIVE BELT BACKUP WHEEL Filed Nov. 29,1949 V m y g a m. T 4 YA L Y 2 w Patented Jan. 1, 1952 UNITED STATESPATENT OFFICE Y 2,581,270

VARIABLE'ABRASIVE BELT BACKUP-WHEEL I Elden N. McVey, Ashtabula Ohio,Application November 29, 1949,1Serial No; 129,959 6 Claims. (Cl..51?14Thisinvention relatestogrinding and polishing apparatus, and'moreparticularly to an improved form of back-up wheel for holding. anabrasive belt or the like incontactwith the material be:- ing-ground orpolished;

. Inthegrinding or polishing-ofimaterial such as metal sheets, strips,knives tools; lids and other such articles that have either a flatsurfacetor gently curving surface, it is customary practice to employ apresseror back-mp wheel to =hold'or back-up an abrasive-belt against thesurface of such material. Itisimportant that a=back-up wheeldevelop'suflicient pressure against theb'elt to-insure maximum belt lifeand maximumcutting action by the individual grains of abrasive.Inaddition, it must be sufficiently flexible to conform with the contourof the material being ground or polished. I

' It'has been found that-a-Wheel having asolid face whichisfiexibleenough to shape itself to the contour of the materialbeing-ground cannot produce sufiicient pressure to effect the maximumrate of cut. Thedesired pressures-can only be developed by wheels havingan intermittent face. Such a wheel allows the piece being ground orpolished intermittently to depress below the surface of' the-wheel, theprojecting surface then contacting the work-piece, thereby eif'ectinganintermittent striking, or saw-tooth,- action-and producinggreatpressurerFurthermore, maximum belt life can only be attained by the applicationof sufficient pressure to cause individual grains of abrasivetopenetrate the --material being ground to adepth wherethe grainspullout of the bond holding them to the belt when-they become dull or worn.Asa result of -"sueh increased pressure as is caused by a wheel havingan intermittent face, the belt-continuously presents'anew cuttingsurface as grains of abrasive are shed, thus insuring-maximum cuttingaction.

It is a primary object of this invention to provide aback-upwheel havingall theabove-enumerateddesirable characteristics.

Otherpbiects and advantageswill becomeapparent as thexfollowingdescription proceeds.

Totheaccomplishment of the foregoing and pulleys.

In said-annexeddrawing:

Fig. 1 is a, longitudinal sectionalview ofjagrinding or polishing.machine Fig; 2 is aside elevation ofa back-upzwheel within the principleof myinventioni.

Fig. azis a front view-.of'the backsup-rwheel shown in Fig. 2', partlyin section;

Fig. 4. is .a front view of a portion ofaback-up wheel having amodi-fiedform of construction;

Fig.- 5- is:a:longitudinal sectional viewof :a specialcontourback-upbar; and

Fig: d is a transverse seetional'view of a:back.- upbar;

Referring: now to thedrawing and :more --espe ciallyto Fig. 1 thereof,the grindingaor polishing machine there indicated is supported by sideframes only one of whichbeing. thereshown. Pairs-of guiding orfeedrollers 2 and-3 are journaled in the side frames- 1, either or. both ofwhich-may be-drivenfrom asuitable source of power-to advance a-inetalsheet or strip 4- through the mach-inst Pulleys- 5 and -6: arejournaledin the side frames I of the upper portion of-themachine; anabrasive belt I passing-aroundsuch Abrasive be1t'8 passes aroundpulleys-'9 and ljou-rnaled in theside frames! in thelower por-tion ofthe machine. A motor" l is-provided to drive the pulleys to effectmovement of the belts '1 and-8t Back-upwheels I 2 are-journaledintheside-frames I of the machine-andserveto hold-"respective belts land Sin grinding engagement with the'workl. g

Referring next to Fig. 2, the back-up-wheel l2 comprisesa shaft l3, a-bus'hi-ng I4, anda hub-lfi, the latter having a flange I centrallyabout its periphery. A pair of identical circular discsor side plates-11- are secured-to the flange I'B- by means of bolts t8, the side platesbeing-formed with aseries of-circumferentially spaced slots I9adjacent-their peripheriesi A- series ofopenings or-vents 20' are formedin each side plate-l1 disposed in circulararrangement about theaxisthereof? A plurality of axially disposedback-up bars areprovided aboutthe peripheryof the wheel; such bars comprising inserts '2 I preferablyof a hard metallic substance, secured between the sidepla tes llbyextending into respective slots their-respective slots:

The inserts 2! are provided witha resilient covering- 23; preferably ofrubber or'-a-plastic material; which covering extends-beyond theperiphery'ofthe sideplates, the cuttingarea- 24 of the covering 23 beingadapted to bear upon the belt at the point of contact of the latter withthe surface being ground or polished. A special contour bar as, forexample, the one shown in Fig. of the drawing, may be provided forworkpieces having a surface of a particular contour.

Thus, the entire assembly is made so that by removal of the bolts 18securing the side plates I! to the flange it of the hub, all of theparts may be quickly disassembled permitting the use of different sideplates and back-up bars to vary the diameter and width of the wheel.Likewise, change may be made in the peripheral surface of the back-upwheel by changing the spacing between the back-up bars (as, for example,by removing alternate bars from the wheel) It will be noted thatincreasing the spacing between the back-up bars produces a more definitestriking, or saw-tooth, action as the latter intermittently press thebelt against the surface being ground or polished, thus increasing thepressure whereby greater cutting action is obtained. Of course, if moreflexible back-up bars are substituted, it is necessary to provide evengreater spacing to obtain the same amount of pressure.

The backup bars may be replaced by others having difierent cutting areasand having covers of varying degrees of resilience. Referring to Fig. 6of the drawing, it is seen that the metallic bar or insert 21 isrectangular in cross-section and thus may be rotated 180 to present agreater cutting area and thus increase the rate of out. It is, ofcourse, obvious that inserts having other cross-sections may be employedwhereby such inserts may be rotated and secured in any number ofselectedrotative positions so that the cutting area which bears upon theabrasive belt may be varied as desired, limited only by the number ofrotative positions available.

The back-up wheel of my invention is thus seen to be quickly adaptableto varying peripheral surface requirements and to work-pieces of avariety.

of conformations.

Fig. 4 shows a back-up wheel having a modified form of construction.Instead of being axially disposed about the wheel, the back-up bars 25are there illustrated as being helically disposed thereabout. It is wellknown to those familiar in the art that at certain critical speeds ofbelt travel, chattering of the belt often occurs. The modified form ofconstruction of back-up wheel shown in Fig. 4 of the drawing serves apurpose in addition to those described with reference to the previousembodiment in that such wheel serves also to prevent chattering of thebelt, since the latter will be held against the work at all points alongthe length of contact without any intermediate portions of belt beingunsupported.

The same result may be obtained with the embodiment previously describedby securing the back-up bars in non-opposed slots of the side plates toeffect helical placement of the bars, or, for finer adjustment, byforming the side plates so as to be relatively rotatably adjustable,whereby the back-up bars may be disposed axially or helically asdesired. Of course, by reducing the spacing between the back-up bars,the intermediate portions of unsupported belt may be correspondinglyreduced, thereby lessening the tendency of the belt to chatter.

It should be noted, however, that the intermittent striking action orsaw-tooth effect caused by circumferential spacing of the back-up barsis most effective where such bars are disposed axially about the wheel.Thus, the degree of helical placement of the bars to reduce possiblechattering of the belt must necessarily correspondingly reduce thecutting action of the belt. Rela tively close spacing of the bars alsosacrifices belt cutting action, since the striking action of theindividual bars is less effective to produce the high pressuresnecessary for a high rate of cut.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equivalent ofsuch, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A back-up wheel for an abrasive belt and the like comprising a pairof axially spaced, substantially radially rigid circular side plates, aplurality of substantially rigid back-up bars extending between saidside plates adjacent their peripheries and removably supported on saidplates in circumferentially spaced relationpand a resilient coveringsurrounding each said backup bar and projecting radially outwardly ofthe peripheries of said side plates.

2. A back-up wheel for an abrasive belt and the like comprising a hub, apair of axially spaced, substantially radially rigid circular sideplates secured on said hub, said side plates being formed with a seriesof circumferentially spaced slots adjacent their peripheries, aplurality of substantially rigid back-up bars extending between saidside plates and removably engaging such slots, and a resilient coveringsurrounding each said back-up bar and projecting radially outwardly ofthe peripheries of said side plates.

3. A back-up wheel for an abrasive belt and the like comprising a pairof axially spaced, substantially radially rigid circular side plates, aplurality of substantially rigid back-up bars extending between saidside plates adjacent their peripheries, -means removably supporting saidback-up bars on said plates in circumferentially spaced relation,whereby said bars may be rotated to present a different face orselectively removed to vary the spacing therebetween, said barsextending parallel with the axis of said wheel, and a resilient coveringsurrounding each said back-up bar and projecting radially outwardly ofthe peripheries of said side plates.

4. A back-up wheel for an abrasive belt and the like comprising a hub, apair of axially spaced, substantially radially rigid circular sideplates removably secured on said hub, said side plates being formed witha series of circumferentially spaced slots adjacent their peripheries, aplurality of substantially rigid back-up bars extending parallel withthe axis of said wheel removably secured between said side plates andengaging such slots, and; a resilient covering surrounding each saidback-up bar and projecting radially outwardly of the peripheries of saidside plates.

5. A back-up Wheel for an abrasive belt and the like comprisin a hub, apair of axially spaced, substantially radially rigid circular sideplates removably secured on said hub, said side plates being formed witha series of circumferentially spaced slots adjacent their peripheries, aplurality of substantially rigid helically disposed, mutually parallelback-up bars removably secured between said side plates and engagingsuch slots, and a resilient covering surrounding eachsaid back-upbar andprojecting radiallyoutwardly from the peripheries of said side plates.

6. A back-up wheel for anabrasive belt and the like comprising a pair ofaxially spaced, substantially radially rigid circular side plates, aplurality of substantially rigid back-up bars displates adjacent theirELDEN N. McVEY.

6 REFERENCES orrEn Number UNITED STATES PATENTS Name Date Cummins June30, 1891 Courtney Dec. 12, 1911 Dade Sept. 27, 1927 Howland July 24,1928 Schulte Jan. 28, 1930 Mason Jan. 17, 1933 Schneider July 28, 1936Herchehrider June 13, 1939 Losey June 19, 1945 Hill Nov. 26, 1946Herchenrider Aug. 2, 1949 Kirstek -1. Jan. 17, 1950

